6 ms·
In terms of distance, sure. In terms of delta-v, the budget for the moon is upwards of 50% that for Mars. EDIT: The 50% figure is from memory, and upon furthe
by andars 9y ago
In terms of distance, sure.
In terms of delta-v, the budget for the moon is upwards of 50% that for Mars.
EDIT: The 50% figure is from memory, and upon further reflection is probably not quite right, so take it with a grain of salt. I just wanted to point out that distance is not the only relevant metric.
- zamalek 9y agoIt makes much more sense to use the moon as a stepping rock. At least my KSP experience has taught me that :)
- rory096 9y ago>The 50% figure is from memory, and upon further reflection is probably not quite right, so take it with a grain of salt. You're actually underestimating. Mars has an atmosphere, so spacecraft can use aerobraking to significantly reduce the delta-v required to get there. The moon has no such benefit — propulsion is required all the way to the surface. The advantage of the moon, of course, is that it's not limited to transfer windows every two years. If there's an emergency or resupply is needed (or you just want to expand the mission), another lander can be sent at any time. (With some restrictions, like hitting your desired landing spot and making sure the sun wasn't in the Apollo crews' eyes at landing. But regardless, no longer than 28 days between windows.)
- WalterBright 9y agoYou need a far bigger (heavier) craft to get to Mars. You'll need years worth of food, water, air, you'll need radiation shielding, much more space per crewmember, more redundant systems and backups, etc. Look at the size of the Apollo.
- Robotbeat 9y agoYears? Absolutely not. Transfer can be done in about 90 days, less (30 days) if you pursue aggressive entry, high orbit refueling, and nuclear thermal propulsion. Assuming you're settling the place and not just doing flags and footprints, transfer time is the important part.
- OtterCoder 9y agoThat's astoundingly quick. 30-90 days is in the same range as crossing the Atlantic via tall ship. With transfer time that low, it really does seem feasible. The two year gaps are a bit rough, but there are plenty of ways to plan for it.
- Tepix 9y agoNowadays ships cross the Atlantic in less than a week.
- OtterCoder 9y agoWell, if any of these silly EmDrives ever work out, maybe we can get Mars down to that time too.
- foxylad 9y agoFor the journey, yes. But for permanent settlement, in both cases you'll need of the order of years-worth of supplies while you become self-sufficient. Back on-topic, the discovery of water on the moon makes this more achievable there; otherwise Mars's resources might have actually meant less resources were required.
- hutzlibu 9y agoBUT ... getting from the moon back to earth is very easy and fast. From the mars not so much.
- valuearb 9y agoThis illustration should help. https://space.stackexchange.com/questions/2046/delta-v-chart-mathematics https://space.stackexchange.com/questions/2046/delta-v-chart...
- andyfal12 9y agoYes, so those two metrics boil down into time cost and fuel cost? Any other costs for just the transit?
- Robotbeat 9y agoNope. Mars is actually lower than the Moon due to atmosphere.
- kurthr 9y agoHowever, you might use a space elevator at L1 or L2 (or both) that allow capture of HEO or launch or inter-system vehicles with only efficient high impulse rocket motors. Note that you could use Spectra/Kevlar or other common high strength materials with a taper ratio of only 4:1 with a lunar elevator. It might take "only" ~50 tons of spectra to hang the weight and allow lifts of a 1000kg or so... its much more doable than earth or mars. https://en.m.wikipedia.org/wiki/Lunar_space_elevator https://en.m.wikipedia.org/wiki/Lunar_space_elevator